The average life expectancy in Japan right now, home to one of the healthiest, longest-living populations in the world, is about 83 years. That's four years longer than in the United States, a decade longer than in much of North Africa, and as many as 30 years longer than some war-torn parts of the world like Sierra Leone.

These global patterns are well-known, but we seldom look at our own communities in the same way.

"Most people appreciate at a country level that there are huge disparities in health between the U.S. and, for example, countries in Africa," says David Fleming, the public health director and health officer for Seattle and King County. "I think what is not as obvious to most people is that you don’t need to go any further than your front door, and most of us are living in communities where those same profound differences occur across much smaller geographic areas."

In fact, that area may span the distance of a stop or two on the subway, or another exit off the highway. In New Orleans, for instance, a couple of miles down Interstate 10 can mean the difference in 25 years in life expectancy, as shown on this map from the Robert Wood Johnson Foundation.

In Fleming's own city of Seattle, life expectancies vary so dramatically between the healthiest and least healthy neighborhoods that it would take those disadvantaged parts of town 100 years to catch up, even if life expectancies were increasing there at the rates of the healthiest countries on earth.

"What this really speaks to is that – because 100 years is way too long to wait – we need to be doing something qualitatively different," Fleming says, "adopting new strategies, new ways of approaching this problem."

We need to think about the differences between adjacent neighborhoods the way we currently think about the differences between America and Haiti. To Fleming, this may mean importing strategies into U.S. cities that have worked in developing countries (like leveraging community health workers, and not just highly trained doctors). And once you start to see cities the way Fleming does, that also leads to a radical change in some of our most basic assumptions about public health.

"In public health, traditionally when we’ve thought about how we’ve allocated resources, we tend to think, 'Well, the same amount needs to go proportionally everywhere,'" Fleming says. "We need to change that. We need to say, 'Actually no, given these huge differences, the fairest way to allocate resources is in proportion to need.'"

The Robert Wood Johnson Foundation has produced a series of maps highlighting these discrepancies, overlaid onto the transportation systems that make these differences appear all the more unacceptable. Here is Kansas City:

And the San Joaquin Valley of California, along U.S. Route 99:

And Minneapolis:

"It’s no mystery about why life expectancy is low in some areas," Fleming says. "Lots of factors influence health. The striking thing is that most of these factors we’re talking about intensely cluster geographically in the same places. Places with low life expectancy are the same places that have high infant mortality rates, high rates of asthma, high rates of obesity."

They're the same places that have few healthy food options, or no sidewalks to encourage walking, or less safety at night, or even greater rates of environmental pollution. This suggests the real public health challenge, as we've written before, is as much about place as it is about people. And that means the solutions should be about place, too.

About the Author

Emily Badger is a former staff writer at CityLab. Her work has previously appeared in Pacific Standard, GOOD, The Christian Science Monitor, and The New York Times. She lives in the Washington, D.C. area.